1. The Field of the Invention
This invention relates to heat sealed laminar products such as I.D. cards, I.D. credit cards or the like and particularly to an article and process employing same useful in the assembly of such products.
2. Description of the Prior Art
Heat sealed laminar products such as I.D. cards, I.D. credit cards or the like are known products or commerce and their desired performance characteristics are well defined. In addition to being compact they must be durable, resistant to wear and to the effects of moisture, sunlight and other conditions. The fabrication of such products ideally should be simple and rapid, with a minimum of manipulative steps which can be accomplished in a routine day to day fashion without the requirement of specialized techniques and knowledge. At the same time, the steps should be such that they can consistently assure that the products obtained uniformly possess the ultimate quality and performance characteristics desired.
In the fabrication of heat sealed laminar products of the type mentioned, the laminar assembly usually has as essential elements thereof, an information bearing card, a transparent plastomeric sheet material as a front member, a plastomeric back sheet member and a heat activatable adhesive system integrated with the elements of the assembly so that sealing can be effected by the application of suitable heat and pressure to the assembly. Usually heated rollers or platen presses are employed in the heat sealing operation and more often than not the assembly is placed in a carrier before heat is applied thereto.
The primary function of the carrier is to protect the elements of the assembly, e.g., the information-bearing element and the plastomeric members from adverse effects that could result if heat were directly applied to the assembly. Carriers heretofore employed essentially comprise two thin sheets coupled together usually along one edge thereof so that the laminar assembly can be quickly and easily inserted therebetween. The sheets can be fabricated of durable, heat resistant plastics or papers but most commonly are fabricated of aluminum which in thin sheets provide the desired degree of durability and optimum heat transmission characteristics.
An outstanding problem in the use of carriers of the type heretofore employed involves extrusion of the heat activatable adhesive system from the laminar assembly as the assembly and carrier are heated. This extrusion is particularly encountered when the carrier and assembly are passed between heated rollers and in most instances, the major portion of the extrudate manifests itself especially at the trailing edge of the heated assembly, e.g., that portion of the assembly which passes through the rollers last. The presence of the extrudate is not only aesthetically displeasing but oftentimes it must be removed especially if the overall dimensions of the laminar product are critical. The existence of this problem diminishes the assurance of the assembler that laminar products of uniform predetermined dimensions will be consistently produced thereby sometimes requiring individual inspection of each product as well as additional finishing operations such as trimming or the like to remove the extrudate.
One method of controlling excess extrudate in the heat lamination operation is disclosed in U.S. Pat. No. 3,679,514 issued July 25, 1972 to Roger J. Kuhn. Said patent discloses a process for eliminating die cutting and trimming of finished laminated plastic I.D. cards. Essentially, the disclosed process involves providing top and bottom protective plastic sheets having the exact dimensions of the finally produced cards and employing "sparse" amounts of adhesive for laminating a data card between the protective top and bottom sheets. The adhesive employed in the preferred embodiment of the disclosed process comprises a medium density polyethylene with or without a heat reactive phenolic. Apparently the maximum thickness of a layer of the combined adhesives is 0.0025 inch on each protective sheet or a maximum thickness of 0.005 inch for both sheets.
In many instances, the use of such a "sparse" amount of adhesive does not provide the desired bonding characteristics between the protective plastic sheets and the data card. Instead, thicker layers of adhesive are essential and adhesive layers conventionally employed in the art oftentimes are in the order of 0.005 inch or greater on each sheet. With layers of such thickness, extrusion of the heat activatable adhesive system can occur and accordingly trimming operations and like problems are not completely eliminated or avoided.
Extrusion of heat activatable adhesive about the edges of the final I.D. or I.D. credit card is an especially important consideration when the card is designed to provide a hole punching capability such as Hollerith hole punching capability. In such I.D. or I.D. credit cards, the edge of the card is employed as a reference for both installing as well as interpreting or reading the capability. Accordingly, minimal tolerance is assigned the edge dimension and in the past such tolerance were obtained by post die cutting of the final laminated card. However, the problem of obtaining such tolerances becomes extremely complicated when a pre-cut laminar assembly is involved providing the potential for extrusion of adhesive on lamination.
The present invention provides a novel carrier and method for using same which is designed to avoid the above-discussed extrusion problem. Accordingly, the carrier and method of employing same can be used in the fabrication of laminar products to provide improved efficiency of operation and assure the production of uniform laminar products which consistently conform to the predesired quality and dimensions.